Continuing research on this project is concerned with the elucidation of hormonal mechanisms controlling membrane permeability and transport processes at the cellular and molecular levels. Within this general framework we are investigating (1) the effect of changes in primary chemical structure on the topochemistry and biological activities of selected neurohypophyseal peptides, (2) the nature of intermediate events and the final effector process in the action of peptide hormones, (3) the phenomena associated with modulation and termination of hormone action, and (4) hypophysiotropic and other factors active on the central nervous system that may derive from neurohypophyseal hormones. BIBLIOGRAPHIC REFERENCES: Isolation of Two Protein Phosphatases from the Plasma Membrane of Canine Renal Papillary Collecting Duct Cells. C.-J. Huang, P.A. Ripoche, H.R. Wyssbrod and I.L. Schwartz. Fed. Proc. 36: 631, 1977. Studies of Phosphorylation-Dephosphorylation Systems of Dog Renal Medulla. P.A. Ripoche, C.-J. Huang, H.C. Li, M.P. Kneussl, L. Reisman, W.N. Scott, H.R. Wyssbrod and I.L. Schwartz. Proc. XXVIIth Intl. Congress of Physiological Sciences, Paris, 1977, in press.